U.S. patent number 3,999,613 [Application Number 05/604,819] was granted by the patent office on 1976-12-28 for tomato harvester header.
Invention is credited to Wellington W. Porter.
United States Patent |
3,999,613 |
Porter |
December 28, 1976 |
Tomato harvester header
Abstract
A header section for a tomato harvester wherein a pair of
counter-rotating discs are moved along a row of tomato plants with
the forward edges below ground level to pick up plants, loose fruit
and soil and deliver them to a pick-up conveyor. A first aspect of
the invention is concerned with a novel structure of the disks and
associated structure whereby plant stems are engaged by the disks,
moved rearwardly and pulled upwardly to sever the plant from the
roots by pulling and breaking rather than cutting. A second aspect
of the invention resides in the resilient coupling of the pick-up
conveyor, upon which the header section is mounted, to the rigid
main frame.
Inventors: |
Porter; Wellington W.
(Waterloo, NY) |
Family
ID: |
27058633 |
Appl.
No.: |
05/604,819 |
Filed: |
August 14, 1975 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
515851 |
Oct 18, 1974 |
|
|
|
|
311254 |
Dec 1, 1972 |
|
|
|
|
Current U.S.
Class: |
171/14; 56/14.3;
56/327.1 |
Current CPC
Class: |
A01D
45/006 (20130101) |
Current International
Class: |
A01D
45/00 (20060101); A01D 055/18 () |
Field of
Search: |
;171/14,27,126,127,130,84-107 ;56/327R,14.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kinsey; Russell R.
Attorney, Agent or Firm: Mc Guire; Charles S.
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of U.S.
application Ser. No. 515,851, filed Oct. 18, 1974, which was a
continuation of U.S. application Ser. No. 311,254 of the same
inventor, filed Dec. 1, 1972, both said prior applications being
now abandoned.
Claims
What is claimed is:
1. Apparatus for movement through a field to assist in crop
harvesting comprising:
a. a frame mounted for movement over the ground;
b. a pair of substantially flat, circular disks arranged in
side-by-side relation with overlapping edges for rotation about
substantially parallel axes through the center of said discs;
c. support means operatively connected to said support frame
maintaining said disks with their forward and rearward edges, with
respect to the direction of movement of the apparatus, respectively
below and above ground level, said axes being tilted forwardly from
the top by an acute angle with respect to the vertical;
d. a pair of dome-shaped elements concentrically arranged about
said axes and sloping downwardly therefrom to the upper surface of
said disks, said elements covering a substantial portion of said
upper surfaces and mounted for rotation with said disks;
e. power driven means imparting rotation through said support means
to said disks in opposite directions with said forward edges moving
toward one another, whereby a layer of earth is lifted by said
forward edges and moved rearwardly upon said disks, the height of
said dome-shaped elements being such that said layer of earth and
material carried thereon are laterally constrained and compacted by
said dome-shaped elements;
f. a plurality of evenly spaced notches extending into the
peripheries of each of said discs and inclined generally in the
intended direction of rotation, said notches being spaced to
provide an edge of the circular disc periphery therebetween,
whereby the stems of plants are engaged between said discs and
pulled upwardly and rearwardly to be severed from the roots, each
of said notches including:
i. a first straight edge extending inwardly from a first point on
the disc periphery at an angle to the radius inclined in the
direction of rotation;
ii. a rounded edge extending from the inner terminus of said first
edge in the direction of rotation; and
iii. a second straight edge extending from the terminus of said
rounded edge to a second point on said disc periphery.
2. The invention according to claim 1 wherein the length of said
edge of the circular disc periphery between each of said notches is
not greater than the width of said notches at the disc
periphery.
3. The invention according to claim 1 wherein the length of said
edge of the circular disc periphery between each of said notches is
not greater than the distance between said first and second
points.
4. The invention according to claim 1 wherein the lower surface of
the upper disc, in the area where said discs are overlapped, is
normally spaced approximately 1/2 inch from the upper surface of
the lower disc.
5. Harvesting apparatus for tomatoes, and the like, comprising:
a. a forwardly disposed header section adapted to sever plants, and
direct plants and fruit rearwardly;
b. a wheel supported feeder section upon which said header section
is supported and including conveyor means adapted to receive
thereon plants and fruit directed rearwardly by said header
section;
c. a shaker section adapted to separate the vines and fruit;
d. a rigid main frame upon which said shaker section is
supported;
e. a plurality of wheels upon which said main frame is mounted for
movement over the ground;
f. resilient means coupling said feeder section to said frame,
whereby said feeder section is movably supported with respect to
said main frame; and
g. opposed biasing means yieldably urging said feeder section
toward a position in alignment with said shaker section.
6. The invention according to claim 5 wherein said resilient means
comprises a bar pivotally connected at opposite ends between frame
members of said feeder section and said main frame.
7. The invention according to claim 6 wherein said opposed biasing
means comprises a pair of springs.
8. The invention according to claim 7 wherein said springs are both
connected at one end of each substantially at the connection of
said bar to said feeder section, and at the other ends of each at
widely spaced points on opposite sides of the connection of said
bar to said main frame.
9. In a tomato harvesting machine of the type movable through a
field to remove plants and fruit from the ground, a header
construction for mounting at the forward end of the machine to
sever plant stems and direct plants and fruit onto the machine,
said header construction comprising:
a. a pair of substantially flat, circular disks arranged in
side-by-side relation with overlapping edges for rotation about
substantially parallel axes through the center of said discs;
b. power drive means imparting rotation to said disks in opposite
directions with the forward edges thereof, with respect to the
intended direction of movement of the harvester, moving toward one
another; and
c. a plurality of evenly spaced notches extending into the
peripheries of each of said discs and inclined generally in the
intended direction of rotation, said notches being spaced to
provide an edge of the circular disc periphery therebetween,
whereby the stems of plants are engaged between said discs and
pulled upwardly and rearwardly to be severed from the roots, each
of said notches including:
i. a first straight edge extending inwardly from a first point on
the disc periphery at an angle to the radius inclined in the
direction of rotation;
ii. a rounded edge extending from the inner terminus of said first
edge in the direction of rotation; and
iii. a second straight edge extending from the terminus of said
rounded edge to a second point on said disc periphery.
10. The invention according to claim 9 wherein the length of said
edge of the circular disc periphery between each of said notches is
not greater than the distance between said first and second points.
Description
BACKGROUND OF THE INVENTION
This invention relates to crop harvesting machinery and, more
particularly, to harvesting of fruits or vegetables growing at or
near ground level, or on low plants, in spaced, individual
rows.
Special machinery has been devised to automatic partially or fully
the harvesting of many different types of food crops. Often such
machinery is unique to a particular crop, being especially tailored
to the harvest of one type of produce and unsuited for use with any
others. While the present invention is disclosed in connection with
the harvesting of tomatoes, it may also be employed in the harvest
of other crops planted in spaced rows particularly those growing
above or slightly below ground level.
Harvesting machines have been previously used which sever the main
stems of plants at or near ground level and transport the vine with
the fruit or vegetable attached to a station for separation
thereof. Severing means used have included rotatable discs with
cutting edges, and conveyors of belt, chain and other types have
been used for transporting the produce through various processing
operations or directly to containers for storage or shipment.
With crops such as tomatoes there is a special problem in machine
harvesting since the fruit must be protected against rough handling
which could cause crushing or bruising. In general, harvesting
machinery for crops of this type represents some compromise between
sturdy or economical apparatus which may damage the produce, and
machinery which handles the fruit or vegetables carefully but is
proportionately more complicated, expensive and fragile. An
associated problem is the tendency of the machine to become clogged
with the vines of the crop being harvested, or with weeds or other
foreign materials.
It is a principal object of the present invention to provide
harvesting apparatus which allows automated gathering of crops
growing above or close to ground level without substantial damage
to relatively fragile fruit, while being simple and economical as
well as durable and reliable in operation.
A further object is to provide a novel and improved means for
harvesting tomatoes by severing the plants one row at a time and
tranporting the fruit laden vines to a separating station.
Still another object is to provide apparatus for digging crops
growing a short distance below ground level and loading them on
conveyor means for automated pick-up and handling in an improved
manner which substantially reduces the liklihood of the machine
becoming clogged.
A still further object is to provide harvesting apparatus of the
type having a section for picking up the crops from ground level
and a further section for additional harvesting operations wherein
the two sections are coupled in a manner providing improved
operation.
An additional object is to provide a tomato harvesting machine of
improved efficiency in picking up and retaining a high percentage
of the crop.
Further objects will in part be obvious and will in part appear
hereinafter.
SUMMARY OF THE INVENTION
The invention comprises novel apparatus for one-row crop
harvesting, gathering and transporting fruit, vegetables, or crop
bearing plants to a station where the fruit or vegetables are
separated from foreign matter. A pair of counter-rotating disks are
supported in side-by-side relation with their adjacent edges
overlapping. The disks are tilted forward so that the leading edges
are below ground level as they are moved along the row, thereby
lifting a layer of soil and moving it rearwardly over the adjacent
portions of the disks. The discs are provided with a series of
notches of unique shape, separated by portions of the circular
peripheral edges of the discs. Means, in the nature of dome-shaped
elements, are provided in association with the disks for laterally
constraining the soil and tending to compress it into a moving bed,
which is delivered to the lower end of the inclined pick-up
conveyor. The structure and relative positioning of the discs are
such that plant stems are severed due to the shape and arrangement
of the notches, and the discs themselves. The stems are severed
after traveling a significant portion of the distance through the
overlapped area of the disks by the upward pull exerted by the
arrangement of the disks, sloping upwardly toward the rear edges.
As the stems are severed the plants are separated from the roots
and transported rearwardly upon the moving bed of soil. The fruit,
vegetables and/or plants are deposited by the disks on a conveyor
chain which allows the soil to fall through, leaving only the
plants and fruit, which are then separated from one another.
The header section, comprising the disks and their supporting
structure, is mounted on the wheeled pick-up conveyor section which
is coupled by resilient means to the main frame. The pick-up
conveyor section, while being urged to an aligned position with
respect to the main frame, is free to move pivotally with respect
thereto, allowing the header section to follow more closely the
ground contour at the point of crop contact. The resilient coupling
feature of the invention may also be employed in harvesting crops
growing in spaced rows a short distance below the ground, such as
beets, turnips, and the like. Such crops are dug up by the
counter-rotating disks and the soil which is dug up with them
serves as a moving bed transporting the vegetables over the blades
and to the open conveyor chain which separates the vegetables from
the dirt and rocks.
BRIEF DESCRIPTION OF THE INVENTION
FIG. 1 is an elevational view of one side of the harvesting
apparatus;
FIG. 2 is an elevational view of the opposite side;
FIG. 3 is a top plan view of the apparatus;
FIGS. 4 and 5 are front and rear views, respectively, of the same
apparatus;
FIG. 6 is a fragmentary side elevational view of the forward
portion of the apparatus in section on the line 6--6 of FIG. 4;
FIG. 7 is a view similar to FIG. 6 of the portion of the apparatus
rearward thereof;
FIG. 8 is a fragmentary, side elevational view of the forwardmost
part of the apparatus;
FIG. 9 is a fragmentary, sectional view in section substantially on
the line 9--9 of FIG. 6;
FIG. 10 is a fragmentary, perspective view of the preferred
embodiment of the header section of the apparatus;
FIG. 11 is a plan view of the overlapped discs shown in FIG.
10;
FIG. 11a is an enlarged plan view of a fragment of the periphery of
one of the discs; and
FIG. 12 is an enlarged sectional view taken on the line 12--12 of
FIG. 11.
DETAILED DESCRIPTION
In the disclosed form, the apparatus is propelled and powered by an
external source, such as a tractor, but a suitable engine, steering
mechanism, etc., could be incorporated, if desired, to make the
machine self-propelled. Tongue 10 extends from the main frame of
the harvesting machine for attachment in the usual manner to a
tractor draw bar. Power take-off drive shaft 12 is connected to the
tractor P.T.O. unit to transmit the necessary power to the main
hydraulic system, denoted generally by reference numeral 14,
through transfer mechanism 13, by conventional power transmission
couplings. The harvesting machine is equipped in conventional
fashion with adjustable slip clutches, relief valves and other such
power transmission safety devices. Hydraulic lines 16 lead from the
manifold, through selectively controlled valves (not shown), to a
plurality of hydraulic motors 18 which drive various individual
conveyors and other moving parts, as described in more detail.
The machine generally comprises header section 20, with which the
present invention is principally concerned, feeder section 22,
shaker section 24, rear lateral conveyor section 26, sorting
section 28, and discharge section 30, all of which may be seen in
FIG. 3. The main frame of the machine is supported for movement on
wheels 32, a pair of tandem wheels 34 are provided to support
feeder section 22, and a smaller pair of wheels 36 adjustably
support header section 20. Platforms 38 are affixed to the frame to
support several workers on each side of sorting section 28, and
platform 40 is provided for the supervisor of the sorting crew at
the head of this section. Manual controls for the aforementioned
valves controlling hydraulic motors 18 are preferably located for
easy access by the supervisor standing on platform 40. A canopy
(now shown) may be mounted in covering relation to the sorting
section to protect workers from sun and rain.
Header section 20 is designed to sever plant stems approximately at
ground level and deliver them, with the fruit or vegetables intact,
to feeder section 22. A pair of disks 42 having notched peripheral
edges, as explained in detail later herein, are supported in
side-by-side relation with their adjacent edges overlapping.
Dome-shaped elements 44 are provided on the upper surfaces of disks
42 and cover a substantial portion thereof. The disks and
dome-shaped elements are fixedly supported on the ends of rotatable
shafts extending from gear boxes 46 through sleeves 48. Drive
shafts 50 are powered by hydraulic pumps 52 and transmit rotation
to the disks in opposite directions so that the leading edges of
the disks move toward one another.
It will be noted from FIGS. 1 and 8 that sleeves 48 and the
rotatable shafts therein, which are concentric with the axes of
discs 42, are tilted slightly forward so that the disks slope
upwardly from their leading edges. Adjustable support mechanism
described later in more detail maintains the leading edges of disks
42 at a desired vertical position, preferably a short distance
below the surface of the soil over which the machine is traveling.
Thus, as the machine is moved along a row of tomatoes, with the
main stems of the plants substantially in a line with the
overlapped portions of the disks, a layer of soil is lifted and
moved rearwardly across the central portions of the disks. Also,
the stems are severed substantially at ground level as they are
engaged between the upwardly sloping, counter-rotating edges of
disks 42. Since the edges of the discs are blunt, and since the
stems of the matured plants are quite tough, the stems are firmly
engaged between the disks, but are not immediately cut off. The
severing action is produced by the engagement of the stem between
the disks combined with the upward pull exerted by the disks as the
engaged portion of the stem travels rearward relative thereto. That
is, the disks are arranged with their adjacent side edges
overlapping and with their rear edges higher than the front edges
at which the stems are initially engaged, thereby producing
combined pulling and shearing forces on the stem.
This action combines with the lateral constraining and compacting
function of domes 44 to contribute greatly to the ability of the
machine to operate without clogging and with minimum droppage,
i.e., failure of the machine to pick up any crops. Since the plants
have already advanced a significant distance rearwardly on the
disks by the time the stems are severed from the roots, there is
much less tendency for the plants or fruit to be thrown outwardly
by the disks and thus fail to be picked up by the harvester. Also,
if the plants are severed, and therefore lying free on the disks,
at or near the point where the forward edges meet, they are more
likely to spin around and become entangled with the disk drive
shafts or the lateral constraining members. This is especially
evident in prior art harvesting apparatus wherein the lateral
constraining means are structurally independent of the disks. In
the present apparatus, wherein the dome-shaped elements which
provide the lateral constraining and compacting function are
rotated integrally with the disks, together with the severing
action which provides for movement of the plants a significant
distance rearwardly on the disks before being freed from the roots,
the plants, weeds or other foreign material are much less likely to
cause clogging of the machine.
Disks 42 may likewise be used for digging crops growing a short
distance below ground level, such as beets, turnips and some
varieties of onions, as well as crops which have previously been
dug or plowed in rows e.g., sweet potatoes. This action is shown
and described in greater detail in connection with later
figures.
From header section 20, the soil, together with the crops and
plants are discharged toward feed section 22. As best seen in FIG.
6, the lower end of inclined pick-up conveyor 58, preferably of the
"potato chain" type, is positioned directly behind the trailing
edges of disks 42, directly in the path of the soil moving
thereover. Conveyor 58 is provided with side shields 60, and the
usual sprockets, idler rolls, and power means (one of hydraulic
motors 18) for imparting rotation in the proper direction. The soil
and fruit-laden plants are discharged from the trailing edges of
disks 42 onto the lower end of conveyor 58 with all or most of the
soil falling off the disks or through the conveyor chain. The
plants are transported upwardly and rearwardly on conveyor 58 and
fall off the upper end to shaker section 24 where the fruit and
vines are separated.
Shaker section 24 includes two continuous belts, one completely
within the other, between side shields 61. Outer or shaker belt 62,
as seen in FIG. 6, receives the plants from feeder section 22 and
is oscillated to shake the tomatoes loose from the vines. Belt 62
is formed of widely spaced links so that tomatoes may fall through
as they become separated while the vines, in general being larger
than the fruit, tend to remain on the shaker belt until they fall
off at the rearmost part of the machine where shaker belt 62 passes
around sprocket 64 and begins its downward travel. Inner or catcher
belt 66 is formed of more closely spaced links so that tomatoes
which fall through belt 62 are retained on the upper surface of
this belt and transported to the upper end thereof where they fall
onto rear lateral conveyor belt 68.
The tomatoes falling throgh shaker belt 62 to catcher belt 66 are
indicated generally in FIG. 7 by reference numeral 70. The vines
from which the tomatoes have been removed and which are being
discharged from the rear of the machine are indicated by numeral
72. Belt 66 passes around sprockets 74, one or more of which is
powered by one of hydraulic motors 18 to drive the belt in the
proper direction at the desired speed, and intermediate idlers 76.
Belt 62 passes over idlers 78 in the lower portion of its travel,
and over idlers 80 on rotating shaker arms 82 in the upper portion.
Details of suitable structure for imparting motion to belt 62 to
dislodge the tomatoes from the plants is explained more fully in
U.S. Pat. No. 3,810,512, of the same inventor.
The tomatoes are transferred from belt 66 to sorting section 28 by
rear lateral conveyor section 26. It will be noted in FIG. 7 that
the end of belt 68 of section 26 which receives the fruit from belt
66 is likewise encircled by belt 62. Belt 68 is also a potato chain
or other such open, continuous belt, and transports the fruit
across the rear of the machine. As shown in FIG. 5, the fruit drops
from belt 68 to sorting belt 84 near the lower end of inclined
conveyor 86. Although the bulk of the vines and plants are
discharged from the rear of the machine by shaker belt 62, some of
the smaller pieces will fall through with the fruit and be
transferred therewith to belt 68. As the tomatoes and pieces of
plants fall from belt 68, the angle of elevation of conveyor 86 is
such that the fruit will roll off the lower end thereof onto
sorting belt 84. The pieces of plants, however, being lighter and
less likely to roll or slide off, will be transported upwardly by
the belt of conveyor 86, of solid rather than open link chain type,
and discharged toward the side of the machine. To assist in the
separation of plant fragments and other light foreign matter from
the fruit at this point, blower 87 is arranged to direct an air
stream across the path of material being discharged from belt 68,
as also seen in FIG. 5.
The fruit deposited on sorting belt 84 is thus relatively free of
plant pieces, rocks and the like. The sorting belt is of the solid
type and is horizontally disposed to transport the fruit from the
rear toward the front of the machine. As previously mentioned,
workmen are stationed along each side of the sorting belt on
platform 38. As the fruit travels along on the sorting belt it is
visually inspected and any unwanted fruit, together with any
remaining foreign matter, is manually removed and thrown back into
the field. Thus, only the tomatoes to be commercially used are
transferred from sorting section 28 to discharge section 30.
The discharge section is laterally disposed in order to discharge
fruit from the side of the machine. From sorting belt 84, the fruit
is deposited on a short, horizontally disposed belt 88, from which
it is transferred to upwardly inclined belt 90 (FIG. 3). The latter
forms a portion of the final discharge conveyor which is pivoted to
the frame at 92 (FIG. 4) and supported by adjustable arm 94. The
position of the top end of the final discharge conveyor may thus be
selectively adjusted for discharging the produce to an adjacent
vehicle, or other receiving means. Both belts 88 and 90 are of the
solid type, as seen in FIG. 3.
Turning now to FIG. 8, various elements of the header section are
shown in greater detail. Sleeve 48 is fixedly attached to
horizontal elements of header support frame 96 which is supported
by upper and lower rods 98 and 100, respectively, attached at their
opposite ends to portion 102 of the rigid main frame. Blade 42 is
closely seen tilted forward with its frontmost edge under the
surface of the ground. The desired angle of tilt may be set by
adjustment of screw jack 103, having one end attached to frame 96
and the other to a fixed support bracket.
Wheels 36, one of which is shown in phantom lines in FIG. 8 are
supported on mechanism attached to support frame 96. The wheel
support mechanism is indicated generally by reference numeral 104
and is adjustable to govern the depth of cut of disks 42. Hydraulic
cylinder 106 is selectively actuable to raise and lower the entire
header assembly, including wheels 36, relative to the main frame of
the harvesting apparatus. Springs 107 assist in supporting the
weight of the forward portion of the header section.
In FIG. 9 is shown the stabilizing mechanism providing a resilient
coupling between the rigid main frame and feeder or pick-up section
22, upon which header section 20 is mounted. Channel members 108
carry, on their facing surfaces, the idler rolls and sprockets for
conveyor 58. The channel members are rigidly affixed to cross
support 110. Stabilizer bar 112 extends between pivotal or
universal-type connections with cross support 110 and the main
support frame. Centering springs 116 are connected between support
110 and outer portions 118 of the main frame. The connection allows
relative movement between the pick-up section and main frame of the
apparatus, thus allowing the disks of the header section, as well
as the pick-up section to follow closely the ground contour
irrespective of the position of the main frame.
The nature and operation of the header section can perhaps best be
seen with reference to FIGS. 10-12 showing portions of the header
section and, in particular, the rotating discs. The drive mechanism
shown in FIG. 10 is somewhat simplified and is preferred over that
indicated in previous Figures. That is, elements such as gear boxes
46, drive shafts 50, etc., have been eliminated and hydraulic
motors 120 are connected directly to the upper ends of parallel
shafts 122 to impart rotation thereto. Shafts 122 extend through
stationary sleeves 48, as in the previously described construction,
discs 42 and domes 44 being affixed to the lower ends of shafts 122
for rotation therewith. Hydraulic lines 124 supply pressurized
fluid from the pumps to power motors 120. Other elements of the
header and feeder sections shown in FIG. 10 are the same as in the
previous construction and are indicated by the same reference
numerals. The outer surfaces of rotating tubes 126, also attached
to the lower ends of shafts 122 for rotation thereby and encircling
the lower ends of stationary sleeves 48, are preferably covered
with rubberized material 128, diamond-tread belt, or other high
traction surface, to assist in engaging and moving the plants and
soil rearwardly.
In FIG. 12, the entire periphery of each of discs 42 is seen to
have formed therein a succession of notches 130 which are generally
inclined in the direction of rotation of the discs, indicated by
arrows 132. The direction of movement of the machine is indicated
by arrow 134. The notches are spaced so that edges 136,
representing portions of the circular disc peripheries, are
provided between each notch. The discs are overlapped at their
adjoining edges to such an extent that the outer periphery of the
upper disc closely approaches the adjacent dome. The precise shape
of notches 130 may be seen more clearly in the fragment of FIG.
12a. A first edge 138 of each notch extends inwardly from
peripheral edge 136 inclined in the direction of rotation with
respect to a radial line of the disc, indicated by line 140. From
substantially straight edge 138, notches 130 are formed with a
generally rounded edge 142 and return to meet the disc periphery
with a second substantially straight edge 144.
The purpose of this notch configuration is to enhance the ability
of the discs to engage plant stems without severing them to detach
the plant from the roots until the plant has moved relative to the
discs to a position well rearward thereon. As shown in the enlarged
and somewhat exaggerated sectional fragment of FIG. 12, plant stem
146 is engaged between the overlapped portions of discs 42 which
are spaced apart by a distance preferably about 3/8 to 1/2 inch.
Although the stem of every plant harvested will not necessarily be
engaged in notches 130 in both of discs 42, most plants will be
engaged in at least one notch, the circular edged portion of the
notches serving as a recess in which the stems tend to be
maintained. At any rate, the edges of discs 42, both within notches
130 and on peripheral edges 136, are blunt and do not significantly
tend to cut the stems. Instead, the stems are severed near root
level by the pulling action of the upwardly sloping discs while
being firmly engaged therebetween.
Discs 42 are made of heavy guage metal, but are flexible in the
peripheral areas outside domes 44 to further enhance their ability
to engage and pull plant stems without cutting them. Notches 130
are preferably about 11/2 inch in width at the periphery of the
discs and are spaced by about 1 inch, thus providing about 38
notches in a disc 30 inches in diameter, which is the approximate
preferred size, although other appropriate sizes may, of course, be
used.
* * * * *